This research project will address the following questions: (1) Does employment during pregnancy have measurable (unfavorable) effects on the course of pregnancy and/or health and development of fetus and infant? (2) Can specific types of occupation of either father or mother be identified that have measurable effects on the course of pregnancy or on the health and developmt of the offspring? The data for this research are assembled in the Child Health and Development Studies, including information on 15,000 families. The procedures will be to investigate relationships of a variety of parental occupations to the course of pregnancy and pregnancy complications; to the health of the newborn, as well as to subsequent growth and development of the child. The data are large enough to control for confounding variables.